In many applications, high-value inductors are a necessity. In particular, this holds for applications in power management. In these applications, the inductors are at least of the order of 1 pH, and must have an equivalent series resistance of less than 0.1Ω. For this reason, those inductors are always bulky components, of a typical size of 2×2×1 mm3, which make a fully integrated solution impossible.
On the other hand, integrated inductors, which can monolithically be integrated, do exist. However, these inductors suffer either from low inductance values, or very high DC resistance values.
US2006157798 discloses a way to mount both an RF circuit including an inductor formed therein and a digital circuit on a single chip. MOSFETs are formed on a semiconductor substrate in regions isolated by an element isolation film. A plurality of low-permittivity insulator rods including a low-permittivity insulator embedded therein and penetrating a first interlevel dielectric film to reach the internal of the silicon substrate is disposed in the RF circuit area. An inductor is formed on the interlevel dielectric film in the RF circuit area by using multi-layered interconnects. A high-permeability isolation region in which a composite material including a mixture of high-permeability material and a low-permittivity material is formed in the region of the core of the inductor and periphery thereof.
JP08017656 discloses a magnetic shielding method and magnetic shielding film forming method of a semiconductor device. The purpose is to minimize the external magnetic effect from inductor conductors formed on a semiconductor substrate. Two inductor conductors are formed on the adjacent positions on the surface of a semiconductor substrate. The inductor conductors are respectively covered with magnetic bodies. In such a constitution, the magnetic fluxes generated by respective inductor conductors are distributed using the magnetic bodies respectively covering said conductors as the magnetic paths so that the magnetic fluxes of the magnetic bodies will be hardly dissipated externally thereby enabling the magnetic effect of respective inductor conductors on any external elements as well as the magnetic coupling with mutual inductor conductors to be avoided.
US2006080531 discloses an implementation of a technology, described herein, for facilitating the protection of computer-executable instructions, such as software. At least one implementation, described herein, may generate integrity signatures of one or more program modules which are sets of computer-executable instructions-based upon a trace of activity during execution of such modules and/or near-replicas of such modules. With at least one implementation, described herein, the execution context of an execution instance of a program module is considered when generating the integrity signatures. With at least one implementation, described herein, a determination may be made about whether a module is unaltered by comparing integrity signatures. This abstract itself is not intended to limit the scope of this patent.
US2003034867 discloses a coil and coil system which is provided for integration in a microelecronic circuit. The coil is placed inside an oxide layer of a chip, and the oxide layer is placed on the surface of a substrate. The coil comprises one or more windings, whereby the winding(s) is/are formed by at least segments of two conductor tracks, which are each provided in spatially separated metallization levels, and by via-contacts which connect these conductor track(s) and/or conductor track segments. In order to be able to produce high-quality coils, a coil is produced with the largest possible coil cross-section, whereby a standard metalization, especially a standard metalization using copper, can, however, be used for producing the oil. To this end, the via contacts are formed from a stack of two ore more via elements arranged one above the other. Parts of the metallization levels can be located between the via elements.
US2003184426 discloses an inductor element having a high quality factor, wherein the inductor element includes an inductor helically formed on a semiconductor substrate and a magnetic material film on a surface of the inductor for inducing magnetic flux generated by the inductor. The magnetic material film preferably includes a first magnetic material film disposed on a lower surface of the inductor, between the substrate and the inductor, and a second magnetic material film disposed on an upper surface of the inductor. The magnetic material film may be patterned according to a direction along which the magnetic flux flows, for example, radial. Since the magnetic material film induces the magnetic flux proceeding toward the upper part and lower part of the inductor, the effect of the magnetic flux generated in the inductor on external circuits may be reduced and the efficiency of the inductor may be enhanced.
Thus there is a need for improved planar coils, not suffering from one or more of the above mentioned disadvantages and drawbacks.
The present invention seeks to provide such an improved coil, not suffering from the one or more drawbacks and disadvantages, which coil further has a high inductance.